As the severity of illness in nursing home (NH) residents continues to increase, so will the required involvement of medical staff including physicians, nurse practitioners and physician assistants in their care. Only a handful of research papers document the limited involvement of physicians in nursing homes and relate them to poor interdisciplinary communication and ineffective treatment, often leading to deleterious resident outcomes, such as avoidable hospitalizations, inadequate pain management, and inadequate pressure ulcer care. New Federal interpretive guidelines to state surveyors draw attention to the importance of physicians who serve as medical directors of NHs. These guidelines motivate an important opportunity to conduct policy relevant research examining how nursing home are responding to these new regulations and examine the role of medical staff. The overarching goal of this R21 project is to examine whether Medicare Claims Files and NH resident assessments (Minimum Data Set) can be utilized to characterize how nursing homes are organizing their medical staff. Key constructs to examine the organization of medical staff in the nursing home will be based on an existing survey of NH medical staff organization funded by the National Institute of Aging (R21 AG025246, PI Dr. Paul Katz). In particular, the aims of this project are to: (1) Develop measures and scales of NH Medical Staff Organization using Billing (NHMSO-B) by aggregating billing information of Medicare beneficiaries while they are in a NH. NH placement will be identified using the Residential History File (RHF) which tracks Medicare beneficiaries location of service utilization using part A Medicare claims and Minimum Data Set (MDS) Assessments. Credentialing data will be used to develop measures of medical staff competency. (2) Test construct validity by comparing NHMSO-B measures to responses from a survey of Medical Directors regarding their medical staff organization (NHMSO) conducted as part of R21 AG025246. (3) Test predictive validity by analyzing the relationships of NHMSO-B measures with hospitalizations and emergency department (ER) use. Since most medical staff services are billed to Medicare, valid NHMSO-B measures based on billing will allow future studies to compare the organization of medical staff in NHs uniformly across the U.S., assessing system-wide determinants of NHMSO-B, including the impact of federal and state regulations. Furthermore, careful studies of the impact of NHMSO-B on quality of NH care will potentially identify best-practice models. 7. Project Narrative Lay Summary: This project aims to develop globally applicable measures of the involvement of medical staff (physicians, nurse practitioners, and physician assistants) in the care of nursing home residents by intelligent use of medical staff Medicare claims for services. The project will test the developed measures comparing to survey responses of medical directors, and to hospitalization and ER use experiences of residents in NHs. [unreadable] [unreadable] [unreadable]